Various mechanisms exist for viewing augmented reality (AR). Many existing systems use a viewer which may be referred to as a head mounted display (HMD), a head worn display (HWD), a heads-up display (HUD), a pair of adapted eyeglasses, smart eyeglasses, also referred to as smartglasses, or other device through which a user will look, or gaze. AR and Virtual Reality (VR) may differ in that while using an AR system, the user expects to be able to see the real world through the viewer, or glass, in addition to augmentation. This may also be referred to as see-through glasses or a see-through viewer. Thus, a usable viewer is either transparent (e.g., to see the actual real world), or will redisplay an image of the real world in real time, for the user. In addition to seeing the actual environment, the augmentations must be displayed in an area of the viewer that is both visible to the user (e.g., appropriate focal length and positioning for the user's pupil(s)), and not directly in the way or blocking key real world objects or information.
Images may be displayed on lens surface as a transmission computer generated hologram. The mathematics of computer generated holograms is well understood. Essentially, holography is made up of three elements: the image, a light source, and the hologram. If any two of those elements is known, the third can be computed. However, holographic displays in existing HWDs may be bulky and difficult to customize for an individual.
An identified problem with an HWD is to cope and compensate for various inter-pupillary distances (IPD) in the population. A typical user's IPD may range from 56 mm to 72 mm. Vertical misalignment may also be a problem for some users. Existing devices such as HoloLens™ available from Microsoft®, MagicLeap Lightwear™ glasses from Magic Leap, Smartglasses from ODG, Google Glass from Google X, and other HWDs, use classical optical components making their devices bulky, but typically adequate optically, for many users. While good optics are desirable, existing HWDs are big and bulky and uncomfortable for many users.